A light field encompasses all the light rays at every point in space traveling in every direction. Light fields are considered four dimensional because every point in a three-dimensional space also has an associated direction, which is the fourth dimension.
Wearable three-dimensional displays may include a substrate guided optical device, also known as the light-guide optical element (LOE) system. Such devices are manufactured by, for example Lumus Ltd. As illustrated in FIGS. 1B-1, 1B-2 and 1B-3, the LOE system 10 uses a single layer wave guide 12 made of two parallel planar surfaces 14a, 14b. Light 16 is coupled into the LOE wave guide 12 using a mini-projector (not shown) and reflector strip 18. FIGS. 1B-1, 1B-2 and 1B-3 illustrate the wave guide 12 of the LOE system 10, showing light 16 entering at three respective angles, The LOE system 10 uses planar micro-reflectors 20a-20n (only two called out for sake of drawing clarity) that are only oriented along one angular direction and are positioned parallel to one another. However, the LOE system 10 only projects a single depth plane, focused at infinity, with a spherical wave front curvature of zero.